Calcium mixed-salt lubricant stabilized



United States Patent 3,125 521 CALCIUM MIXED-SALT L UBRICANT STABILIZED AGAINST WATER CONTAMINATION Wiliiam Kenneth Detweiler, Westfield, William E. Lifson,

Union, and Frederick L. Jonach, Short Hills, N.J.,

assignors to Esso Research and Engineering Company,

a corporation of Delaware No Drawing. Filed Nov. 15, 1961, Ser. No. 152,680

7 Claims. (Cl. 25232.7)

This invention relates to fluid or semi-fluid lubricants comprising calcium salts of fatty acid in oil, and containing a small amount of a stabilizing additive to prevent formation of gel in the presence of water. Particularly, the invention relates to mineral lubricating oil containing calcium salt of acetic acid and calcium salt of a C to C fatty acid, and a lubricating oil detergent additive as a stabilizer.

Recently, lubricating compositions comprising oil thickened with calcium salt of acetic acid, in combination with calcium salt of higher molecular weight fatty acid, e.g. C to C fatty acid, have found Wide spread use in commercial applications. These mixed-salt lubricants have good anti-wear and load-carrying ability, which properties made them commercially successful. One large commerical outlet for lubricants of this type is for lubrication of the cylinders of marine diesel engines.

Marine diesel engines are now in wide use. In these engines there has always been a serious wear problem with regard to this piston, the piston rings and the surface of the cylinder liner. This problem of wear has been aggravated by the recent growing tendency to use low cost residual type fuel oils containing 2 to 4 wt. percent sulfur, as compared to previously used distillate fuel oils having under 1.5% sulfur. Unfortunately, because of their high sulfur content, the residual fuels tend to greatly increase the linear and cylinder wear, primarily due to corrosive acids formed by the combustion of the sulfur, which acids corrode the steel surfaces of the engine.

It had been found that requirements for lubrication of marine diesel engines operating on high sulfur fuel can be met by thickening mineral oil with 3 to 12, preferably 5,to 9 wt. percent of a thickener comprising calcium salt of acetic acid or its anhydride in combination with calcium salt of. fatty acid containing 7 to 12 carbon atoms, in a molar ratio of about 11.5 to 25 mole equivalents of said acetic acid or anhydride per mole equivalent of said O, to C fatty acid. This results in a viscous or semi-fluid lubricant which prevents wear, neutralizes the corrosive acids, furnishes the necessary extreme pressure properties and otherwise meets all the requirements for marine diesel lubrication. However, lubricants of this type have been found very susceptible to contamination by small amounts of water which tends to gel the otherwise semi-fluid lubricant. This water contamination can occur due to atmospheric condensation, thus interfering with the storage and handling of the lubricant. The resulting gelling is very undesirable since it interferes with the forced feeding of the lubricant through small diameter feed lines through which it is sprayed upon the diesel engine cylinders. It has now been found that by the incorporation of about 0.1 to 10.0 wt. percent of certain stabilizing additives, that the ability of the lubricant to adsorb water contamination without gel formation is materially increased. In addition, it has been found that these stabilizing additives also generally increase the spreadability of the lubricant over the hot upper cylinders of marine diesel engines.

The stabilizing additive is preferably a lubricating oil detergent additive, i.e. a material which has the properties of promoting engine cleanliness when incorporated into a crankcase motor oil. Exactly why these detergent additives are useful in preventing gel formation of the calcium mixed salt lubricant by Water is not exactly known. However, it is believed that these detergent additives prevent gel by dispersing the water and/or forming a protective coating on the salts.

The detergent additives which are operable include the petroleum sulfonates, synthetic alkyl aryl sulfonates, various alkyl phenates, alkyl phenate sulfides, phosphosulfurized olefin polymers, various combinations of these additives, etc. Following are specific descriptions of several of the above types of detergent additives.

Petroleum sulfonates generally used as lubricating oil detergents are the oil-soluble alkaline earth metal salts of high molecular weight sulfonic acids. These sulfonic acids are produced by the treatment of petroleum oils of the lubricating oil range with fuming sulfuric acid and generally have molecular weights of about 300 to 700 e.g., 350 to 500. Petroleum sulfonates are well known in the art and have been described in numerous patents, e.g. U.S. 2,467,176.

Detergent sulfonates can also be derived synthetically from relatively pure alkyl aryl sulfonic acids having from about 10 to 33 carbon atoms per molecule. For example, sulfonated products of alkylated aromatics such as benzene, toluene, Xylene, and naphthalene, alkylated with olefins, or olefin polymers of the type of polypropylene, polyisobutylene, etc. can be used.

Specific examples of the above two types of sulfonates include calcium petroleum sulfonate, barium petroleum sulfonate, calcium di-C alkyl benzene sulfonate, barium di-Cg alkyl benzene sulfonate and calcium C alkyl benzene sulfonate; wherein said C alkyl group is derived from diisobutylene; said C alkyl group is obtained from tripropylene and said C alkyl groups are obtained from tetraisobutylene.

The above sulfonates can be either neutral sulfonates, i.e. where the sulfonic acid is neutralized with an equal mole equivalent amount of metal base, or the sulfonates may be of the so-called high alkalinity type. In the latter case, additional metal base, in excess of that required for simple neutralization, is reacted with the sulfonic acid to form an alkaline product which can then be blown with carbon dioxide. Recent work has indicated thta such so-called high alkalinity sulfonates are nothing more than dispersions of neutral sulfonates and a carbonate of the metal used, which dispersions are believed to exist in the form of colloidal sols. In any event, the term sulfonate as used herein and in the appended claims includes both neutral sulfonates and so-called high alkalinity (or high metal content) sulfonates.

The alkyl phenates used in this invention are well known and include the oil-soluble alkali and alkaline earth groups per phenol group. Said alkyl group can be OH II wherein R represents an alkyl group, a is 0 to 4, b is O to 10 and c is 1 to 5. The metal used to form the phenate can be aluminum, cobalt, chromium, sodium, lead, tin, etc., or the alkaline earth metals as calcium, barium, strontium and magnesium. Each alkyl group can contain to 20, e.g., 7 to 12 carbon atoms, either straight or branched chain. Specific examples of the phenate sulfides include barium tertiary octyl phenol sulfide, calcium, tertiary octyl phenyl sulfide, barium-calcium tertiary octyl phenol sulfide, barium tertiary amyl phenol sulfide, calcium tertiary amyl phenol sulfide, barium nonyl phenol sulfide, etc.

High alkalinity (i.e. high metal content) alkyl phenate and phenate sulfides are also included in the above descriptions. These materials are prepared by reacting the alkyl phenol or phenol sulfide with an excess of metal base and then neutralizing the basic product, generally by C0 blowing.

The phosphosulfurized olefins are also well known and are prepared by reacting an olefin or an olefin polymer with P 5 to form a dithiophosphoric acid. More specifically, the phosphosulfurized olefins are generally prepared by reacting phosphorus pentasulfide with a polyolefin having 2 to 6 carbon atoms per monomer group and a molecular weight in the range of 500 to 200,000 Staudinger. Particularly preferred are the P 5 treated polybutenes having a Staudinger molecular weight in the range of 600 to 2,000. The phosphosulfurized polyolefins are normally prepared by reacting the phosphorus pentasulfide and polyolefin at a tempearture of 150 to 600 F. for a period in the range of 0.5 to 15 hours. The preparation of these phosphosulfurized polyolefin detergent additives is more fully described in US. Patent 2,875,188.

The lubricants of the invention can be prepared by coneutralization of a mixture of the acids with the hydroxide and/or carbonate of calcium, in situ in mineral lubricating oil. The coneutralized material is dehydrated by heating to about 250 to 350 F., preferably 300 to 320 F. It is generally desirable to use a slight excess of base, e.g. lime, in order to form a slightly alkaline final product, e.g. 0.05 to 0.2 wt. percent alkalinity as measured in terms of NaOH. This excess alkalinity acts to further neutralize corrosive acids during use and also imparts conditions of greater stability. After dehydrating, the composition can be cooled and the stability additive added. For economy purposes in heating during large scale manufacture, concentrates of 35 to 50 wt. percent of the mixed calcium salts in oil can be made by the in situ preparation technique and then diluted with additional oil to form the finished lubricant.

Various additives can be added to the finished lubricant in amounts of 0.1 to 10.0 wt. percent, based on the weight of the finished lubricant. Among additives that can be added are corrosion inhibitors such as sodium nitrite, lanolin, wool grease stearine; antioxidants such as phenyl a-naphthylamine; auxiliary extreme pressure agents; dyes; etc.

The invention will be further understood by reference to the following examples which include a preferred embodiment of the invention.

EXAMPLE I A semi-fluid calcium mixed salt lubricant was prepared having the following formulation:

Weight percent Glacial acetic acid 3.84 Wecoline AAC acid 0.93 Lime 2.70

Naphthenic lubricating oil of SUS. at 210 F 92.33 Phenyl a-naphthylamine 0.20

The lime and about an eighth of oil were intimately mixed, followed by the addition of about a third of the Wecoline AAC acids (a commercial mixture of coconut acids consisting of about 46 wt. percent capric, about 28 wt. percent caprylic and about 26 wt. percent lauric acids). Then all the glacial acetic acid was added, while mixing, at a slow rate so as to keep the temperature of the reaction mass below 180 F. The remainder of the Wecoline AAC acid was then added, the reaction mass was thoroughly mixed and then heated to a maximum temperature of about 305 F., which was held for two hours after which the heat was turned ofi and cooling begun. About a twelfth of the 80 SUS. oil was added. Upon the material cooling to 220 F., the phenyl a-naphthylamine was added. Next, the remainder of the oil was added. The resulting product was passed through a Cornell homogenizer and filtered through a mesh Cuno strainer.

Various amounts of detergent A, which is a mineral oil solution containing about 70 wt. percent of a phosphosulfurized polyisobutylene, was added to the above described mixed salt lubricant. This phosphosulfurized polyisobutylene was prepared by reacting polyisobutylene of about 780-1100 (Staudinger) molecular weight with 15 wt. percent, based on the weight of polyisobutylene, of P 5 at about 425 F. for about 8 hours under a nitrogen atmosphere.

Various amounts of a lubricating oil detergent designated detergent B was added to the above described mixed salt lubricant. A typical preparation of detergent B is as follows: An oil solution of nonyl phenol consisting of 60 to 65 wt. percent mono-nonyl phenol and 40 to 35 wt. percent of di-nonyl phenol (the nonyl groups are tripropylene groups) was heated with pentahydrate barium hydroxide at about 260 F. for about 3 hours. The mixture is then blown with nitrogen until the water content of the reaction mixture was reduced to about 0.8 to 1.6 wt. percent. The composition was maintained at 260-275 F. and was blown with CO for several hours until a weight ratio of Ba/CO of between 3.4:1 to 4.421 was obtained. The preceding results in an oil dispersion of high alkalinity barium nonyl phenate which is next reacted at 300 F., while nitrogen blowing, with an oil solution of P 5 treated polyisobutylene of 7801100 mol. weight (detergent A). The resulting composition is filtered.

Following are the relative amounts of reacting materials in parts by weight used in preparing detergent B.

P 8 treated polyisobutylene 27.0 Ba(OI-I) .5H O as BaO 10.6 Alkyl phenol 11.7 CO 2.5 Inert, mineral diluent oil 48.2

Varying amounts of water were added to the composition prepared above and a series of centrifuge tests were carried out by centrifuging at 1500 r.p.m. for 4 hours in a centrifuge having an effective centrifuging radius of 27 centimeters.

The compositions tested, and the results obtained are summarized in the following table:

6 What is claimed is: 1. A composition suitable for the lubrication of the Effect of Detergents and Water on Stability of Calcium Mixed Salt Lubricant Vol. percent water added O 0.005 0.02 0.40

Detergent, Wt. percent 0.0 0.5 A 1.5 A 0.5 B 0.0 0.5 A 1. 5 A 0.5 B 0.0 0. 5 A 1.5 A 5 B 1 5 A 5 B Centrifuge Test:

Percent Serum 3.0 3.0 3. 3.0 50 4. 0

Percent Solids 0.7 0.8 0.4 1.0 Trace 0.3

Percent Gel 0.0 0.0 3. 6 0.0 50 2. 7 Percent Gel Sohds O. 7 0.8 0. 85 0.85 4. 0 1. 0 0.8 1. 0 60 3.0 0.9 1.2 0, 7 3, 0

As seen by the preceding table, the lubricant per se, i.e.

with 0% water and 0% detergent, showed 0.7% total separation in the centrifuge test of gel and solids. The 3% serum separation merely means that a clear oil layer equal to 3% of the total sample separated. While this serum separation is not desirable, it does not constitute a serious drawback since the serum layer, i.e. the layer of clear oil will readily mix back into the total composition upon stirring. On the other hand, the gel and solids formation is more serious since simple mixing will not blend this form of precipitate into the total composition. In fact, this gel and solids separation is a serious problem since it can result in clogging of small diameter feed lines of forced centralized lubrication system. It will be noted that the addition of detergents A and B had no significant effect where no free Water was added to the lubricant.

Upon the addition of 0.005 vol. percent free Water to the mixed salt lubricant, the gel formation was considerable, going to 3.6%, while the total amount of gel and solids was 4.0%. However, the presence of 0.5 Wt. percent detergent A prevented gel formation. The presence of 0.5% detergent B also had a beneficial effect as noted by the low gel plus solids figure of 1.0%. The data shows that free water contaminating the unprotected mixed-salt lubricant causes gel formation which tends to separate, while the detergents prevent said gel formation. When the water contamination reaches 0.2 vol. percent, gel formation in the unprotected mixed salt lubricant increases to 50%, with 50% serum also formed. Adding detergents A and B materially protects the lubricant against this gel and serum formation. The data at 0.40% water contamination still shows the effectiveness of detergents A and B.

To further illustrate the invention, 7 wt. percent of calcium sulfonate is added to 93 wt. percent of the semifluid mixed salt lubricant of Example I. The sulfonic acid portion of the calcium sulfonate can be prepared by alkylating benzene with polypropylene to obtain an average molecular Weight of about 450. The resulting composition will have improved resistance to water gelling and good spreadability, i.e. ability to wet and spread evenly on hot lubricated metal surfaces.

In sum, the present invention is directed to the addition of detergent additives to a calcium mixed lubricant prepared from acetic acid or its anhydride and C to C fatty acid. The detergent additives prevent gelling caused by water contamination of the mixed salt and also generally improves the spreadability of the lubricant. If prevention of gelling by water is the main concern, then 0.1 to 4.0 wt. percent of detergent additive will generally suflice for most conditions. This amount of detergent will also increase spreadability. However, larger amounts of detergent, e.g. 4 to wt. percent, will improve spreadability even more while still improving the resistance to gelling.

spreadability as used herein is the ability of the lubricant to spread on a hot metal surface. Spreadability can be measured by dropping one drop of lubricant on a hot plate (e.g. having a surface temperature of 415 F.) and measuring the diameter to which the drop spreads. The larger said diameter the greater the spreadability.

upper cylinders of marine diesel engine comprising a major amount of mineral lubricating oil, about 3 to 12 wt. percent of calcium mixed salts of acetic acid and C to C fatty acid in a molar ratio of said acetic acid to said fatty acid of 11.511 to 25:1 and about 0.1 to 10.0 wt. percent of lubricating oil detergent additive capable of stabilizing said composition against separation upon water contamination of said composition, said detergent additive being selected from the group consisting of oilsoluble alkali metal and alkaline earth metal salts of alkyl phenol having about 5 to 20 carbon atoms in each alkyl group and about 1 to 3 alkyl groups per phenol group, P 5 treated polymers of C to C olefins, said polymers having molecular weights in the range of about 500 to 200,000 Staudinger, and reaction products of said salts of said alkyl phenols and said polymers.

2. A composition according to claim 1, containing said metal salt of an alkyl phenol.

3. A composition according to claim 1, containing said P S treated polyolefin.

4. A composition according to claim 1, wherein the amount of said detergent additive is about 0.1 to 4.0 wt. percent.

5. A composition suitable for the lubrication of the upper cylinders of marine diesel engines consisting essentially of mineral lubricating oil, about 5 to 9 wt. percent of calcium mixed salts of acetic acid and C to C fatty acid in a molar ratio of about 11.5 to 25 mole equivalent of acetic acid salt per mole equivalent of C to C fatty acid salt, and about 0.1 to 4.0 wt. percent of a lubricating oil detergent additive capable of stabilizing said composition against separation upon water contamination of said composition, said detergent additive being selected from the group consisting of oil-soluble alkali metal and alkaline earth metal salts of an alkyl phenol having about 5 to 20 carbon atoms in each alkyl group and about 1 to 3 alkyl groups per phenol group, P 8 treated polymers of C to C olefins, said polymers having molecular weights in the range of about 500 to 200,000 Staudinger, and reaction products of said salts of said alkyl phenols and said polymers.

6. A composition according to claim 5, wherein said detergent additive is phosphosulfurized polyisobutylene, said polyisobutylene having a molecular weight ranging from about 780 to about 1100.

7. A composition according to claim 5, wherein said detergent additive is prepared by reacting a barium hydroxide with nonyl phenol, blowing with CO to obtain a weight ratio of Ba to CO of about 3.421 to 4.4: 1, then reacted with a phosphosulfurized polyisobutylene.

References Cited in the file of this patent UNITED STATES PATENTS 2,846,392 Morway et a1 Aug. 5, 1958 2,969,324 Knapp Jan. 25, 1961 2,989,464 Panzer June 20, 1961 3,018,249 Morway et al. Jan. 23, 1962 3,044,961 Morway et al. July 17, 1962 

1. A COMPOSITION SUITABLE FOR THE LUBRICATION OF THE UPPER CYLINDERS OF MARINE DIESEL ENGINE COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL, ABOUT 3 TO 12 WT. PERCENT OF CALCIUM MIXED SALTS OF ACETIC ACID AND C7 TO C12 FATTY ACID IN A MOLAR RATIO OF SAID ACETIC ACID TO SAID FATTY ACID OF 11.5:1 TO 25:1 AND ABOUT 0.1 TO 10.0 WT. PERCENT OF LUBRICATING OIL DETERGENT ADDITIVE CAPABLE OF STABILIZING SAID COMPOSITION AGAINST SEPARATION UPON WATER CONTAMINATION OF SAID COMPOSITION, SAID DETERGENT ADDITIVE BEING SELECTED FROM THE GROUP CONSISTING OF OILSOLUBLE ALKALI METAL AND ALKALINE EARTH METAL SALTS OF ALKYL PHENOL HAVING ABOUT 5 TO 20 CARBON ATOMS IN EACH ALKYL GROUP AND ABOUT 1 TO 3 ALKYL GROUPS PER PHENOL GROUP, P2S5 TREATED POLYMERS OF C2 TO C5 OLEFINS, SAID POLYMERS HAVING MOLECULAR WEIGHTS IN THE RANGE OF ABOUT 500 TO 200,000 STAUDINGER, AND REACTION PRODUCTS OF SAID SALTS OF SAID ALKYL PHENOLS AND SAID POLYMERS. 